Those going to “The Battle of the Sexes” expecting 0nly a bit of lightweight nostalgia had best gird their loins. There’s more going on here than a re-creation of a oddball moment in our cultural history.

Yes, this retelling of the famous 1973 tennis match between Billie Jean King and Bobby Riggs has its share of humor and historic earmarks. (Those costumes. Those hairstyles.)

But you’ll leave Jonathan Dayton and Valerie Faris’ film (they were the pair behind “Little Miss Sunshine”) struck by how relevant its issues remain, by the anger percolating just beneath the surface, and for its implicit warning that the bad old days may be making a comeback.

Simon Beaufort’s script wastes little time in setting up the basic conflict. In 1970 nine of the best female tennis players rebelled against the U.S. Lawn Tennis Association over the disparity between prize money awarded men and women.

Told they cannot be there, Heldman shoots back: “Why? Because I’m a woman? Or because I’m Jewish?”

Right there “Battle of the Sexes” draws its line. Progress versus the reactionary status quo.

The upshot is the creation of the all-women Virginia Slims tennis circuit.

In a parallel plot line we eavesdrop on former tennis champ Billy Riggs (Steve Carell), now immersed in post-career boredom.

Riggs fritters away his days at a make-work job at his father-in-law’s business; at night he hangs with his drinking buddies, taking bets that he can beat anyone at tennis while tethered to two large dogs or substituting a frying pan for his raquet.

His high-society wife (Elisabeth Shue) makes him attend Gamblers Anonymous meetings, which he breaks up by declaring that the problem isn’t that these people gamble, but that they’re bad gamblers. Winners don’t need support groups.